According to mmafighting.com:
Both sides have verbally agreed to the fight, and barring any setbacks, contracts are expected to be signed shortly.
The fight is expected to be a part of the upcoming DREAM light heavyweight tournament, which will also feature an opening round bout between Melvin Manhoef and Tatsuya Mizuno.
Gegard “The Dreamcatcher” Mousasi (28-3-1)
Loss Muhammed Lawal – Decision (Unanimous) Strikeforce
Win Gary Goodridge – TKO (Punches) K-1
Win Rameau Thierry Sokoudjou – TKO (Punches) Strikeforce
Win Renato Sobral – TKO (Punches) Strikeforce
Win Mark Hunt – Submission (Straight Armbar) Dream 9
Jake O’Brien (13-3)
Win Toni Valtonen – Decision (Unanimous) FF 27
Win Dave Hess – Submission (Kimura) MMA Big Show
Loss Jon Jones – Submission (Guillotine Choke) UFC 100
Win Christian Wellisch – Decision (Split) UFC 94
Loss Cain Velasquez – TKO (Punches) UFC FN 14
Rumored card so far:
– Shinya Aoki vs. Tatsuya Kawajiri
– Gesias “JZ” Cavalcante vs. Katsunori Kikuno
– Alistair Overeem vs. TBA
Light-heavyweight grand prix opening round
– Melvin Manhoef vs. Tatsuya Mizuno
– Gegard Mousasi vs. Jake O’Brien